most in-theme cards require it on the field, and "Shining Sarcophagus" can search any card that mentions it
In addition, most of the trap cards it uses have ridiculous effects that activate from the hand, and with the exception of the Ajin series, they are based on the Major Arcana
Planeswalkers, though, are closer to Enchantments than Sorceries and even though I said I would play more Instants and Sorceries (and stop having them be the first thing I cut) I NEVER play Planeswalkers
The second could be a temporary reprieve if you run a good amount of Spells, but may backlash against you if your opponent gets monsters out, which well-built "Prophecy" Decks will have a diverse way of doing so
If I cast two Charging Badgers and you cast one Raise the Alarm, we've both spent exactly two mana, but you've gotten the better of me
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